Well tool and anchoring means therefor



March 27, 1956 M. w. HAlNES 2,739,653

WELL TOOL AND ANCHORING MEANS THEREFOR Filed June 5, 1950 2 Sheets-Sheetl j? .1. i ft? ee INVENTOR. Mflecus W J ll/N55,

March 27, 1956 M. w. HAINES 2,739,653

WELL TOOL AND ANCHORING MEANS THEREFOR Filed June 5, 1950 2 Sheets-Sheet2 IN VEN TOR.

MARCUS W EMA/Es,

United States Patent WELL TOOL AND AN'QHORING lt [EANS THEREFOR MarcusW. Haines, Long Beach, Calif., assiguor to McGatiey-Tayior Corporation,Long Beach, Calif., a corporation of California Application June 5,1950, Serial No. 166,127

22 Claims. (Cl. 166-136) This invention relates to well tools which arelowered into oil wells for effecting or permitting of operations ortreatments for improving or otherwise controlling production of thewells, and to means for anchoring such tools, particularly bridge plugsand the like, at various locations in the Well bores according to theoperation or treatment desired.

It is an object of this invention to provide an improved tool of thecharacter described, incorporating said anchoring means, for plugging awell at any location in the bore thereof.

It is a further object of this invention to provide an improved tool andanchoring means wherein the tool may be anchored at a desired locationresponsive to a lifting movement of the means by which the tool ispositioned in the well.

It is also an object to provide an improved plug tool which may bereleased without the use of shear pins, explosive charges, ornecessitating that the tool or the positioning means therefor be turnedor rotated, and wherein an anchoring grip with the well casing as wellas release of the tool from the positioning means, is efiectedresponsive to a lifting movement of said positioning means.

It is another object of this invention to provide a tool such asdescribed wherein the anchoring means is urged by a force applying meansto grip the casing, and restrained While being positioned, and releasedso as to be self operative upon release of the tool from the means bywhich it is positioned in the Well.

It is another object of this invention to provide an anchoring means fortools such as described, wherein opposing casing gripping members extendcompletely across the tool in abutting relation one to the other whengripping the casing, thereby providing a rigid and full cross sectionalsupport, more elfectively sustaining loads on the tool and the grippingmembers and maintaining the tool securely anchored to the casing.

It is an additional object of this invention to provide in a tool suchas described a novel sealing cup of plastic material constructed andarranged to form an elfective seal between the tool and casing and whichin contradistinction to seals formed of rubber and the like, will not,when disintegrated, cause jamming or interference with pumps and movingparts of apparatus handling well fluids containing particles of rubber.

It is another object of this invention to provide a frangible well plugsuch as described in which the body thereof as well as the cup seal isformed of a frangible plastic material which is chemically inert to wellfluids, and wherein the plug as a whole is free of rubber or materialwhich might prove detrimental to pumps and valves handling well fluids,containing bits of rubber or like materials.

It is a further object of this invention to provide a well plug such asdescribed which may be disintegrated by hammer blows as may be effectedby dropping any wire line supported weight thereagainst, instead ofrequiring a drilling operation to remove the plug.

2,739,653 Patented Mar. 27, 1956 It is a further object of the inventionto provide a bridge plug of the character described which is adapted tobe lowered into a Well on a bailer containing cement slurry, or otherwell treating substances, and to be anchored in the desired position inthe well bore and released from the bailer upon operation of the bailerto discharge the cement or other well treating substance.

This invention possesses many other advantages and has other objectswhich may be made more easily apparent from a consideration of oneembodiment of the invention. For this purpose there is shown a form inthe drawings accompanying and forming part of the present specification.This form will now be described in detail, illustrating the generalprinciples of the invention; but it is to be understood that thisdetailed decription is not to be taken in a limiting sense, since thescope of the invention is best defined in the appended claims.

Referring to the drawings:

Figure 1 is a side elevational view of a tool embodying the presentinvention as it would appear while being lowered into a well casing;

Figure 2 is an enlarged vertical sectional view taken on the line 2-2 ofFigure 1;

Figure 3 is a cross sectional view taken on the line 33 of Figure 2; l

Figure 4 is a view corresponding to Figure 2, showing the tool releasedfrom the lowering means and anchored in the casing; v

Figure 5 is a cross sectional view taken on the line 55 of Figure 4; and

Figure 6 is a fragmentary plan view of the seal cup for forming a sealbetween the casing and the body of the tool.

One embodiment of the present invention as shown in the accompanyingdrawing, consists of a tool known as a bridge plug and which generallycomprises a body 7, sealing means 8 fixed thereto for forming a sealbetween the body '7 and the well casing 9, anchoring means 10 carried bythe body below the sealing means for gripping the casing and setting theplug, means 11 for releasably connecting the tool with means 12 forlowering the tool into the well and positioning it therein, and arestraining means 13 for restraining the anchoring means until relativemovement is eifected between the plug and the positioning means 12.

As here shown, the releasable meansof connection 11 and the restrainingmeans 13 are carried by the positioning means 12 and are arranged sothat the release of the anchoring means takes place before release ofthe tool from the positioning means 12, upon the initial upward orlifting movement of the positioning means, a continuation of thismovement releasing the tool.

A force applying means 14 carried by the tool body 7 constantly urgesthe anchoring means 10 toward anchoring contact with the well casing butthe restraining means 13 prevents such movement until the initiallifting of the lowering means takes place. Thus, as the anchoring meansis self operating upon release from the restraining means, any upwardmovement of the tool such as might invert or impair the sealing means isprevented during continued lifting of the positioning means as necessaryto release the tool.

The body 7 is preferably formed of a suitable frangible plastic materialand so constructed as compared to plugs or tools made of drillable orfrangible metals, that the tool is easier to handle, more economical asto production, readily disintegrated by hammer blows without requiring adrilling operation to remove it, is subject to being detachablyconnected with means for positioning it in the well, through the use ofa comparatively simple and easily operated means, and capable ofwithstanding theloads usually .imposedonsuch tools. Thus, the body 7instead of being of solid formation or having walls or portions ofconsiderable thickness in cross section is longitudinaily ribbed anddeeply fluted, the ribs or fins 7a being of substantially equal radialextent.

The sealing means 8 comprises a pair of similar annular disks 3a andSbpreferably formed of a flexible and resilient plastic material. Each ofthese disks is formed with a series of radial slots or notches 80forming radial tongues 8d. The disk 8b is laid upon the disk 8a so thatthe tongues of disk 8b overlie the notches or slots 8c of disk 8a andoverlap the tongues on the latter. The two disks in this relativearrangement are removably fastened together and in place on a flange 7bon the body 7 by means o'f'a'clamping ring 15, bolts 16 and nuts 17.Thus,secured to the body7 the disks 8a and 8b form a cup seal which, asshown in Figure 2, will yield upwardly and by-pass well fluid as thetool is lowered into the well casing butwill be urged into sealingcontact with the casing 9 responsive to pressure of well fluid or cementslurry located above the tool when the latter is stopped or anchored inthe well.

The means -11 for releasably connecting the tool with the means 12 forpositioning the tool in a well, as here shown, comprises alongitudinally slotted socket member 22 which is adapted to telescope atubular extension 23 of the body 7, in such manner that bowed leafsprings 24 mounted in the slots 25 will frictionally grip the tubularextension. A shoulder 26 internally of the member 22 limits the movementof the extension 23 into the socket member. Each spring 24 is secured atone end, as at 27, to the member 22, and its other end is freely movablebut retained in an annular groove 28 in the member 22, said grooveopening into the slots 25.

The means for lowering the tool into the well and positioning ittherein, may comprise a wire line, not shown, or any suitable meansoperable from the top of the well. The tubular member 29 here shown asscrew threaded into the upper end of the socket member 22 isrepresentative of the means 11 for positioning the tool and may be asection of tubing supported by a wire line or otherwise manipulated fromthe top of the well or may be considered as the lower end of a bailersuch as used to deposit cement slurry or chemicals in a well and in anyevent is illustrative of a lowering and positioning means by which thetool hereof may be positioned in a well and detached from the socketmember 22 responsive to lifting the latter from frictional telescopicengagement with the extension 23.

As here shown, the anchoring means comprises a pair of similar eccentriccasing gripping members 30 and 31 mounted to turn on pins 32 in a slotor opening 33, extending transversely through the body 7. The slot 33 isformed between two diametrically opposed ribs of the group of ribs 7a,the pins '32 being mounted in these ribs so that the gripping membersare guided between the ribs in turning from a retracted position, lyingwithin the slot 33 as shown in Figures 1, 2 and 3, into casing grippingposition shown in Figure 4.

The gripping members 30 and 31 are arranged to be turned simultaneouslyto dispose arcuate and serrated gripping elements 34 thereon in grippingengagement with the casing, said elements being formed of a suitablehard metal and secured to the peripheries .of eccentric portions of themembers by means of suitable fastenings 35. The teeth on each of thegripping elements 34 extend in a curvilinear row and face downwardly asit is the purpose thereof to make these gripping members selftighteningin anchoring the plug against downward movement rather than upwardmovement. The gripping members 3 and 31 preferably are "formed as hereshown of frangible plastic material.

The force applying means. 14 comprises a retractible spring 3.6 mounted.inan. axial Ibor'e. 37 inrthe body 7,

one end of the spring being fastened to a pin 38 at the lower end of thebore and the other end being connected with an eye 3? provided at thelower ends of a pair of flexible elements 40 which are fixed to thecasing gripping members 39 and 31 by means of suitable fastenings 41.With this arrangement, the spring 36 urges the members 39 and 31 to turnsimultaneously and equally for disposing the gripping eiements 3dthereon in contact with the well casing.

The means 13 for restraining the casing gripping members 30 and 31 ashere shown comprises a pin or rod 42 having a tubular head 43 pivoted ona pin 44, mounted in the socket member 22, said pin having a tapered endportion 42a disposed to extend between the casing gripping members 30and 31, as a wedge to prevent movement thereof out of retracted positionas shown in Figure 2. A flap valve 45 preferably formed of a flexibleand resilient plastic material is mounted in the extension 23 so as toclose an opening 23a in a bottom wall 231) of. the extension, said pinextending through said opening and holding the valve 45 open when inposition to restrain the members "32, but releasing the valve whenretracted, as shown in Figure 4. Thus, the valve '45 closes an axialbore which'is formed through the body '7 by the tubular extension 23,the opening 23a, the transverse opening or slot 33 and the bore 37.

"The opposed peripheral faces of the casing gripping members 30 and 31are grooved'as at 39a to accommodate the tapered end 42a of the pin 42in a wedging contact with said members as shown in Figure 4, the innerportions or bottoms 30b of said grooves being of reduced Width toaccommodate the flexible elements 40 as shown in Figure 3.

With reference to Figure 2, it will be apparent that as the diameter ofthe plug body 7 is less than the inside diameter of the casing 9, whilethe sealing cup 8 is of greater diameter than the inside diameter of thecasing but will yield upwardly, the tool may be lowered into the wellcasing without interference as the fluid will by-pass it while beinglowered. On the lifting of the means 11, the pin 42 will be lifted clearof the casing gripping members 30 and 31, which are immediately moved bythe spring 36 and the flexible elements 40 from retracted position shownin Figure 2, to gripping position shown in Figure 4. Continued upwardmovement of the socket member 22 will remove the latter from frictionalholding contact with the extension 23 and thus release the plug andwithdraw pin 42 which permits the flap valve 45 to close the opening23a, thus completing the'seal formed by the plug. The weight of anysubstance above .the plug will tend to move the plug downward, and thustighten the grip of the eccentric gripping members 30 and 31 andincrease the sealing action of the 'cup seal 8. Thus the grippingmembers 30 and 31 are self actuating after initially contacting thecasing. Forces tending to urge the plug downwardly cause the anchoringmembers to turn on their axes, so

' as to increase the anchoring action and positively lock the plugagainst downward movement.

When the gripping members 30 and 31 are in casing gripping positron theopposed surfaces thereof abut each other, thereby providing a rigid andfull cross sectional suppo'rtior effectively sustaining loads on thegripping members and maintaining the tool securely anchored in place.The resistance offered by the well fluid above the sealcupb and thefrictional contact thereof makes it possible to lift the socket member22 to release the casing gripping members 30 and 31 and detach the plug.

Any'object, not shown, adapted to be lowered into the wellon a wire lineand having appreciable weight may be employed for effecting hammer blowson the plug to disintegrate it when it is desired to unplug the wellbore.

While the anchoring means is here shown as incorporated with a bridgeplug, it should be noted that it may be employed with other types oftools which are adapted to be anchored at various locations in the boreof a Well.

I claim:

1. In a well tool adapted to be lowered into a well casing and anchoredtherein, a body, means for releasably connecting the body with a meansfor lowering-the tool into the well; a pair of eccentric casing grippingmembers mounted on the body for rotation between a retracted positionand a position to grip the casing; a spring connected at one end withthe body, flexible elements connected with the other end of the springand to said gripping members for rotating said members into grippingcontact with the casing under the force of said spring; and meansforming a wedge between said gripping members to hold them in retractedposition and releasing said gripping members upon release of the bodyfrom said means for lowering the body into the well.

2. In a well tool adapted to be lowered into a Well casing and anchoredtherein, a body, means for releasably connecting the body with a meansfor lowering the tool into the well; a pair of eccentric casing grippingmembers mounted on the body for rotation between a retracted positionand a position to grip the casing; a spring connected at one end withthe body, flexible elements connected with the other end of the springand to said gripping members for rotating said members into grippingcontact with the casing under the force of said spring; a wedge membercarried by said means for releasing the body, extending between andholding said gripping members against rotation into casing grippingposition and being withdrawn from holding position upon release of thebody.

3. In a well tool adapted to be lowered into a Well and anchoredtherein, a body, sealing means mounted on the body for forming a sealbetween the wall of the well bore and the body, means releasablyconnected with the body at a point above the sealing means, with a meansfor lowering the tool into the well, operating to release said body onthe lifting of said lowering means, anchoring members mounted on thebody beneath said sealing means for rotation between a retractedposition and a position for gripping the wall of the Well bore andanchoring the tool thereto, a retractile spring mounted on the bodybeneath the anchoring members, flexible elements connected with saidanchoring members and said spring for simultaneously rotating saidanchoring members into said gripping position, said body having anopening therein, a restraining member carried by said releasing meansand extending through said opening into contact with said anchoringmembers for restraining rotation thereof and being withdrawn fromrestraining contact with said anchoring member and from said opening onrelease of said body, and a valve on the body operating to close saidopening when the said restraining member is withdrawn therefrom.

4. In a well tool adapted to be lowered into a well and anchoredtherein, a body, means on the body forming a seal between the wall ofthe well bore and said body to prevent downward flow of fluid past theseal, anchoring members mounted on the body below the seal for rotationbetween retracted position and a position in which said members grip thewall of the well bore, spring means urging said anchoring members intosaid gripping position, said body having an opening therein afiordingaccess to the anchoring members from a point above said sealing means, arestraining member mounted in said opening and contacting said anchoringmembers to hold them against rotation into position to grip the wall ofthe well bore, means for releasably connecting said body at a pointabove the seal with a means for lowering the tool into the well, beingoperable to release the tool responsive to lifting of the means forlowering the tool into the well, means connecting said restrainingmember with said releasing means for withdrawing the restraining memberfrom the said anchoring members and from said opening upon the liftingof the means for lowering of said tool, and a valve closing said openingon withdrawal of said restraining member from said opening.

5. In a tool adapted to be lowered into a well and anchored therein, anelongated body having an axial bore extending therethrough, and anopening extending transversely thereof and intersecting said bore; meansmounted on the body above said opening for forming a seal be tween thewall of the well bore and the body; eccentric anchoring members mountedin said transverse opening for rotation between a retracted position anda position for anchoring the body in the well; spring means in saidbore, urging said anchoring members into anchoring position; arestraining member removably mounted in said bore for holding saidanchoring members against movement into anchoring position; means forreleasably connecting the upper end of said body with a means forpositioning the tool in the well, operating to release the tool onlifting movement of said positioning means; means connecting saidrestraining member with said tool releasing means for withdrawal fromsaid bore upon the lifting of said positioning means; and valve meansoperable to close the bore at a point above said transverse opening whensaid restraining means is withdrawn from the bore.

6. In a well tool adapted to be lowered into a well casing and anchoredtherein, a body, means for releasably connecting the body with a meansfor lowering the tool into the well; a pair of eccentric casing grippingmembers mounted on the body for rotation between a retracted positionand a position to grip the casing; spring means for rotating saidgripping members into contact with said casing, said gripping membershaving gripping surfaces formed to cause the gripping members to turnand increase the gripping action thereof responsive to forces directeddownwardly on said body after said surfaces have contacted said casing,and means forming a wedge engageable with opposed surfaces of saidgripping members to hold them in retracted position, operable to releasethe gripping members upon the release of the body from the means forlowering the body in the well.

7. In a well tool adapted to be lowered into a well casing and anchoredtherein, a body, means for releasably connecting the body with a meansfor lowering the tool into the well; a pair of eccentric casing grippingmembers mounted on the body for rotation between a retracted positionand a position to grip the casing; spring means for urging said grippingmembers into contact with said casing, and means extending downwardlybetween and holding said gripping members in retracted position andmoving upwardly and releasing said gripping members responsive torelease of said body.

8. In a well tool adapted to be lowered into a well casing and anchoredtherein, a body, means for releasably connecting the body with a meansfor lowering the tool into the well; a pair of eccentric casing grippingmembers mounted on the body for rotation between a retracted positionand a position to grip the casing; spring means for urging said grippingmembers into contact with said casing, means extending downwardlybetween and holding said gripping members in retracted position andmoving upwardly and releasing said gripping members responsive torelease of said body, and valve means on said body above said grippingmembers held in open position by said holding means for said grippingmembers and closing responsive to upward movement of said holding means.

9. In a well tool adapted to be lowered into a well casing and anchoredtherein, a body, means for releasably connecting the body with a meansfor lowering the tool into the well; a pair of eccentric casing grippingmembers mounted on the body for rotation between a retracted positionand a position to grip the casing; spring means for urging said grippingmembers into contact with said casing, means extending downwardlybetween and holding said gripping members in retracted position and mov-'in'g upwardly and releasing said gripping members responsive to releaseof said body, and means o'nsaid body controlling the flow of fluidtherethrough, including a valve on the body above said grippingmember's, held in open position by said holding means for said grippingmembers and closing when said holding means for said gripping members ism'oved upwardly past the valve after releasing said gripping member.

10. In a well plug adapted to be anchored in a Well casing: a plug body;a tubular member fixed to said body; a tubular member mounted inslidable telescopic relation with the first named tubular member forseparation therefrom; means for connecting the second named tubularmember with means for positioning the plug in said casing, means of saidbody engageable with the well casing and adapted to support cementdeposited thereon, said second named tubular member being separable fromthe first named tubular member responsive .to the upward movement ofsaid positioning means; means on one of said tubular members engagingthe other of said tubular members to yieldably resist separationthereof; casing gripping members on said body; means for urging saidgripping members into casing gripping positions; means operativelyconnected with one of said tubular members for holding said grippingmembers out of casing gripping position; said last named means releasingsaid gripping members upon separation of said tubular members; said bodyhaving a passage extending therethrough, and a valve on said bodymovable to open and close said passage, said last named means holdingsaid valve in position opening said passage when said gripping membersare retracted, and releasing said valve for closing said passage whensaid tubular members are separated.

11. In a well plug adapted to be anchored in a well casing: a plug body;a tubular member on said body; a tubular member mounted in slidabletelescopic relation with the first named tubular member for separationtherefrom; means for connecting the second named tubular member withmeans for positioning the plug in said casing, packing means on saidbody engageable with the casing and adapted to support cement depositedthereon, said second named tubular member being separable from the firstnamed tubular member responsive to movement of said positioning means ina direction away from said body; means on one of said tubular membersengaging the other of said tubular members to yieldably resistseparation thereof; casing gripping members on said body; means forurging said gripping members into casing gripping position; and meansoperatively connected with said second named tubular member for holdingsaid gripping members out of casing gripping position; said last namedmeans releasing said gripping members upon separation of said tubularmembers.

12. In a Well plug adapted to be positioned in a well casing: a plugbody; a tubular member on said body; a tubular member mounted inslidable telescopic relation with the first named tubular member forseparation therefrom; means for connecting the second named tubularmember with means for positioning the plug in the casing, packing meanson said body engageable with the casing, said second named tubularmember being separable from the first named tubular member responsive toupward movement of said positioning means; means on one of said tubularmembers engaging the other of said tubular members to resist separationthereof; said last named means yielding and permitting separation ofsaid tubular members responsive to said upward movement of saidpositioning means, means on said body operable for gripping the casingto anchor the plug in the casing responsive to separation of saidtubular members; and means connected with one of said tubular membersfor restraining operation of said gripping means while said; tubularmembers are telescopically connected.

tubular member mounted in slidable telescopic relation with the firstnamed tubular member for separation therefrom; means for connecting thesecond named tubular member with means for 'positioning th'e plug in theeasing, packing means on said body engageable with the casing, saidsecond named tubular memberbeing separable from the first named tubularmember responsive to movement of said positioning means; means on one ofsaid tubular members engaging the other of said tubular members toresist separation thereof; said last named means yielding and permittingseparation of said tubular members responsive to said movement'of saidpositioning means; said body and tubular members providing a passagetherethrough; a valve for closing said passage; means operativelyconnected with said second named tubular member engaging said valve andholding it in open position when said tubular members are telescopicallyconnected; said last named means moving to release said valve forclosing said passage upon separation of said tubular members anchoringmeans on said body operable for anchoring the body to the casingresponsive to separation of said tubular members; said valve-engagingmeans engaging said anchoring means and restraining operation of saidanchoring means while said tubular members are telescopically related.

14. In a well plug adapted to be anchored in a well casing: a body;means on said body adapted to be releasably connected with means forpositioning the body in the casing; gripping members mounted on saidbody for movement between a retracted position and a casing grippingposition; means for urging said gripping members into engagement withsaid casing; a packer on said body above said members engageable withthe casing, said body having a passage extending therethrough; valvemeans for controlling said passage; and means adapted for connectionwith said positioning means operable for holding said gripping membersin retracted position and said valve means in open position; said lastnamed means being operable to release said gripping members and saidvalve means upon release of said body from said positioning means.

15. A well tool adapted to be released from means for lowering it in awell casing and to be anchored to the casing, including: a body havingmeans thereon cooperable with the lowering means to releasably connectthe body thereto; a pair of casing gripping members mounted on said bodyfor movement from a retracted position to casing gripping position; saidgripping members having opposed peripheral portions disposed to abut oneanother when said gripping members are in casing gripping position;packing means on said body above said gripping members for engaging thecasing; restraining means cooperable with said gripping members toreleasably hold said gripping members in said retracted position; saidrestraining means releasing said gripping members upon release of saidbody from said lowering means; and means on said body for urging saidgripping memebers into casing gripping position upon release of saidrestraining means.

16. A well tool adapted to be released from means for lowering it in awell casing and to be anchored to the casing, including: a body havingmeans thereon cooperable with the lowering means to releasably connectthe body thereto; a pair of casing gripping members pivotally mounted onsaid body for movement from a retracted position to casing grippingposition; said gripping members having opposed peripheral portionsdisposed to abut one another in a plane extending transversely of saidbody through the pivots of said gripping members when said grippingmembers are in casing gripping position; packing means on said bodyabove said gripping members for engaging the casing; restraining meanscooperable with said gripping members 'to releasably hold said gri pinmember in said retracted position; said restraining means releasing saidgripping members upon release of said body from said lowering means; andmeans on said body for urging said gripping members into casing grippingposition upon release of said restraining means.

17. A well tool adapted to be released from means for lowering it in awell casing and to be anchored to the casing, including: a body havingmeans thereon cooperable with the lowering means to releasably connectthe body thereto; a pair of casing gripping members pivotally mounted onsaid body for movement from a retracted position to casing grippingposition; said gripping members having opposed peripheral portionsdisposed to abut one another in a plane extending transversely of saidbody through the pivots of said gripping members when said grippingmembers are in casing gripping position; packing means on said bodyabove said gripping members for engaging the casing; restraining meanscooperable with said gripping members to releasably hold said grippingmember in said retracted position; said restraining means releasing saidgripping members upon release of said body from said lowering means; andmeans on said body for urging said gripping members into casing grippingposition upon release of said restraining means; each of said grippingmembers having a casing gripping surface curved eccentrically about theaxis of the gripping member.

18. A well tool adapted to be released from means for lowering it in awell casing and to be anchored to the casing, including: a body havingmeans thereon cooperable with the lowering means to releasably connectthe body thereto; a pair of casing gripping members pivotally mounted onsaid body for movement from a retracted position to casing grippingposition; said gripping members having opposed peripheral portionsdisposed to abut one another in a plane extending transversely of saidbody through the pivots of said grippingmembers when said grippingmembers are in casing gripping position; packing means on said bodyabove said gripping members for engaging the casing; restraining meanscooperable with said gripping members to releasably hold said grippingmembers in said retracted position; said restraining means releasingsaid gripping members upon release of said body from said loweringmeans; and means on said body for urging said gripping members intocasing gripping position upon release thereof; said gripping membershaving casing gripping surfaces which cause the gripping members to turnabout their axes and increase the gripping action thereof responsive toforces directed downwardly on said body after the gripping members havecontacted the casing.

19. In a well tool adapted to be anchored in a well casing: a body; apair of easing gripping members mounted on said body for movement from aretracted position into casing gripping position; means cooperable withsaid gripping members for releasably holding said members in retractedposition; and means for urging said gripping members into casinggripping position upon release of said holding means; said grippingmembers having marginal portions for gripping the casing and forabutting one another, respectively; said abutting portions abutting oneanother and being opposite said gripping portions when the latter gripthe casing.

20. In a well tool adapted to be anchored in a well casing: a body; apair of casing gripping members pivotally mounted on said body formovement from a retracted position into casing gripping position; meanscooperable with said gripping members for releasably holding saidmembers in retracted position; and means for urging said grippingmembers into casing gripping position upon release of said holdingmeans; said gripping members having marginal portions for gripping thecasing and for abutting one another, respectively; said abuttingportions abutting one another and being opposite said gripping portionswhen the latter grip the casing; said gripping surfaces being curvedeccentrically about the axes of the gripping members.

21. In a well plug adapted to be anchored in a well casing: a bodyhaving means for releasable connection with means for positioning thebody in the casing; gripping members pivotally mounted on said body formovement between a retracted position and a casing gripping position;means for resiliently urging said gripping members into engagement withsaid casing; packing means on said body engageable with the casing; andmeans connectable with and withdrawable by said positioning means forreleasably holding said gripping members in retracted position when saidbody is connected to said positioning means; said holding meansreleasing said gripping members upon release of said body from saidpositioning means.

22. In a well plug adapted to be anchored in a well casing: a bodyhaving means adapted for releasable connection with means forpositioning the body in the casing whereby said body will be releasedresponsive to axial movement of the positioning means in one directionrelative to said body; means on said body engageable with said casing toresist movement of said body in said direction; gripping memberspivotally mounted on said body for movement between a retracted positionand a casing gripping position; means for resiliently urging saidgripping members into engagement with said casing; and means cooperablewith said positioning means so as to be positioned and withdrawn thereby'for releasably holding said gripping members in retracted position;said last named means releasing said gripping members upon release ofsaid body.

References Cited in the file of this patent UNITED STATES PATENTS406,162 Donnell July 2, 1889 1,260,036 Perry Mar. 19, 1918 1,842,107Lytle Jan. 19, 1932 1,913,548 Hodges June 13, 1933 2,092,843 HendersonSept. 14, 1937 2,227,347 Johnson Dec. 31, 1940 2,547,461 Hampton Apr. 3,1951

